A little story:
I was working as a workshop leader in a project with refugees. One of the participants came from Irak. As there was no shared language of Dutch, English or Arabic and we were both tiered from the long days of work we sat silently next to each other for a while waiting till the end of the break would come. Suddenly he started humming a couple of notes. I was surprised but after a short silence replied his melody. We hummed back and forth for a while till the break was finished and returned to the working space in silence.